Over the past 20 years, there have been many developments of methods and apparatuses for sensing chemical materials, biochemical materials and environmental toxicity in the sensor field. Monitoring of chemical materials and biochemical materials is very important to not only medical diagnosis and bio-warfare applications but also to basic research.
Recently, the use of nanosized materials in the fields of industry or science is dramatically increasing. Such nanoparticles have higher reactivity than existing materials due to properties of a small size and a wide specific surface area, and their harmful influences on human bodies and environment have been reported through many studies. For this reason, attempts have been being made in many aspects to improve a detection range of nanosized toxic materials. A typical detection method includes labeling with a quantum dot, a fluorescent marker, a dye, and the like. This labeling detection method may be widely used in molecule detection but needs to consider photochemical decomposition, pH dependency, time limitation, high costs, and the like. To pursue a diverse range of targets and overcome the limitations of a labeling method, current technology development focuses on building a multimodal system to achieve sensitivity improvement, label-free detection, cost reduction and analytical molecule detection.
A cantilever sensor is a sensor which detects a fine material by applying a piezoelectric mechanism using a piezoelectric material, and is primarily manufactured through a micro electro mechanical system (MEMS) process. A microcantilever sensor is greatly classified into a microbalance principle and a surface stress principle in its application. The former is a dynamic mode that measures a change of resonant frequency with a change in mass and spring constant of a cantilever, and the latter is a static mode that measures strain with a change in surface stress by a specific reaction on a microcantilever. This microcantilever sensor features high sensitivity, high selectivity and labeling-free detection, and may be used to analyze pathogen including DNA, marker proteins and small molecule biomaterials. However, because a cantilever sensor is a sensor responsive to a change in mass, there are drawbacks that even when an unwanted material is attached to the sensor surface, the cantilever sensor responds thereto and the cantilever sensor cannot identify a detected molecule.
A surface-enhanced Raman scattering (SERS) sensor is a new concept of Raman sensor that overcomes low reactivity noted as a drawback of a conventional Raman sensor by amplifying a reactivity value of a Raman sensor using a nanostructure or nanoparticles, and has an advantage of discriminating a detected chemical molecule through signal analysis. However, to manufacture an SERS sensor, a complex nanostructure and various processes are needed, so it takes much time to manufacture and a manufacturing cost is high, resulting in low economic efficiency, and there are drawbacks of a lack of macro uniformity and a lack of compatibility with an MEMS.